High density polyurethane foams



United States Patent HIGH DENSITY POLYURETHANE FOAMS Francis M, Kujawa,Tonawanda, and Blaine O. Schoepfle, Snyder, N.Y., assignors to HookerChemical Corporation, Niagara Falls, N.Y., a corporation of New York NoDrawing. Continuation-impart of application Ser. No. 348,776, Mar. 2,1964. This application May 18, 1966, Ser. No. 550,917 1 1 17 Claims.(Cl. 260-25) ABSTRACT OF THE DISCLOSURE A composition suitable for usein preparing a polyurethane foam having a density of at least 4 poundsper cubic foot is prepared by mixing a hydroxyl-containing polymerhaving a hydroxyl number between about 25 to 900, and asccondary-phophonate that is non-reactive in the urethane reaction. Suchcompositions are reacted with a polyarylpolyisocyanate, in the'presenceof a foaming agent to produce a polyurethane foam having a uniform cellstructure.

This is a continuation-in-part of Ser. No. 348,776, filed Mar. 2, 1964,now abandoned, which is a continuation-inpart of Ser. No. 248,275, filedDec. 31, 1962, now Patent No. 3,257,337.

This invention relates to polyurethane compositions that areparticularly suitable for use in the production of higher density foamproducts. In another aspect, it relates to a process for improving thecompatibility and mixing characteristics of components in a polyurethanefoamable composition.

Particularly desirable polyurethane foams are produced by reacting ahydroxyl-containing polymer with a polyarylpolyisocyanate in thepresence of a foaming agent, and optionally a catalyst. The productionof higher density foams-4 poundsper cubic foot and higherin relativelythick sections, 2 inches in thickness or greater, requires foamablecompositions having relatively lower activity than compositions used forproducing the more usual 2 pound per cubic foot density foams. The lowerreaction rates prevent too rapid a build-up of heat due to the heatof-reaction of the components. However, especially with the polyurethanefoams made with polyarylpolyisocyanates, the lower reaction rates alsotend to provide more time for the components toseparate or stratifyduring the course of the reaction process. This phenomenon leads tonon-uniform distribution of components, and to non-uniform foamstructures in the final foam products.

Accordingly, it is an object of this invention to provide a polyurethanecomposition particularly suitable for the production of higher densityfoams. Another object of the invention is to provide a method-foreffectively preventing the stratification or separation of thecomponents of a foamable composition containing a polyarylpolyisocyanateduring the reaction process. A further object is to improve thecompatibility and mixing characteristics of the components of such afoamable composition. These and other objects of the invention willbecome more apparent upon consideration of the following detailedspecification.

The objects of the invention are accomplished by the method ofincorporating in the foamable composition a second degree ester ofphosphonic acid (secondary phosphonate) that is non-reactive in theurethane reaction. Thus, in accordance with this invention there areprovided 3,400,085 Patented Sept. 3, 1968 2 g polyurethane compositionshaving incorporated therein a phosphorus compound having the formula:

Y ROI OR I.

wherein Y is oxygen or sulfur, and R is selected from the groupconsisting of alky-l, halogen substituted alkyl, aralkyl and arylradicals that are not substituted by radicals that are reactive in theurethane reaction. The hydrocarbon radicals preferably contain from 1 to20 carbon atoms, more preferably from 1 to 10 carbon atoms. The alkylgroups can be substituted with one or more of the same halogen atoms,such as chlorine or bromine, or with the mixture of halogen atoms, suchas a mixture of chlorine or bromine atoms.

More particularly, the polyurethane composition of the inventioncomprises (A) a hydroxyl-containing polymeric material having a hydroxylnumber between about 25 and 900, (B) a second degree ester of phosphonicacid of the type described in the preceding paragraph, (C) apolyarylpolyisocyanate, and (D) a foaming agent. Optionally, catalystsand other additives can be used in the compositions. Particularlysuitable for use as the hydroxyl-containing polymer of this inventionare the alkyd resins containing an adduct of hexahalocyclopentadiene.

Suitable second degree esters of phosphonic acid that can be used in thepractice of the invention include dimethyl methylphosphonate, diethylmethylphosphonate,

diethyl methylphosphonate, diethyl amylphosphonate, diamylamylphosphonate, dilauryl methylphosphonate, diphenyl methylphosphonate,dibenzyl methylphosphonate, diphenyl cresylphosphonate, dimethylcresylphosphonate, bis(chloropropyl) chloropropylphosphonate,bis(chloropropyl) propenyl-Z-phosphonate, bis(2,3-dibromopropyl)2,3-dibromoproyl phosphonate, and bis(betachloroethyl) vinylphosphonate; and the corresponding sufur analogs such as dimethylmethylthionophosphonate, diamyl amylthionophosphonate and the like.

In the preparation of the polyurethane compositions of the invention, itis preferred to use a hydroxyl-containing polymeric material having ahydroxyl number between about 25 and 900. Such a polymeric material canbe a polyester, a polyether or mixtures thereof. Generally, thehydroxyl-containing polymers of the invention have a molecular weight inthe range from 200 to about 4,000.

Rigid or flexible polyurethane foams are produced in accordance withthis invention. The rigid polyurethane foams utilize highly branchedhydroxyl rich polyesters or polyethers having a hydroxyl number ofbetween about 200 and 900. The flexible polyurethane foams utilizelinear, relatively hydroxyl-poor polyesters or polyethers havinghydroxyl number of between about 25 and 100. If a polyester or polyetherwith a hydroxyl number between about and 200 is employed, a semi-rigidpolyurethane foam is usually obtained.

The polyesters are the reaction products of a polyhydric alcohol and apolycarboxylic compound, said polycarboxylic compound being either apolycarboxylic acid, a polycarboxylic acid anhydride, a polycarboxylicacid ester, a polycarboxylic acid halide or mixtures thereof. Thecarboxylic compounds can be aliphatic, cycloaliphatic, aromatic, orheterocyclic and either saturated or unsaturated. Among thepolycarboxylic compounds which can be used to form the polyester are:maleic acid; fumaric acid;

phthalic acid; isophthalic acid; terephthalic acid; tetrachlorophthalicacid; aliphatic acids such as oxalic, malonic, succinic, glutaric andadipic; 1,4-cyclo-hexadiene-1,2-dicarboxylic acid and the like.Additional polycarboxylic compounds which can be used to form thepolyester are Diels-Alder adducts of hexahalocyclopentadiene and apolycarboxylic compound containing aliphatic carbon-tocarbonunsaturation, wherein the halogen is selected from the group consistingof chlorine, bromine, fluorine and mixtures thereof, for example:l,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid;l,4,5,6-tetrachloro-7,7-difiuorobicyclo-(2.2.1)-S-heptene-2,3dicarboxylic acid: 1,4,5,6,7,7-hexabromobicyclo (2.2.1) 5-heptene-2,3-dicarboxylic acid; 1,4,5,6-tetrabromo-7,7 difiuorobicyclo(2.2.1)-5-heptene-2,3-dicarboxylic acid; and the corresponding acidanhydrides, acid halides, and acid esters. Mixtures of any of the abovepolycarboxylic compounds can be employed.

At least a portion of the total polyhydric alcohol component shouldcomprise a polyhydric alcohol containing at least three hydroxyl groups.Where a very rigid structure is desired, the entire alcohol componentcan comprise a trifunctional alcohol such as glycerol. Where a lessrigid foam product is desired, a difunctional polyhydric alcohol such asethylene glycol or l,4-butanediol can be utilized as part of thepolyhydric alcohol component. Suitable polyfunctional alcohols includediethylene glycol, propylene glycol, polypropylene glycols, polybutyleneglycols, glycerol, hexanetriol, trimethylol propane, trimethylol ethane,mannitol, cyclohexanediol-l,4; glycerol monoethyl ether and the like.The ratio of the polyhydric alcohol such as glycerol to the polybasicacid can be expressed as the hydroxyl-carboxyl ratio, which can bedefined as the number of moles of hydroxyl groups to the number of molesof carboxyl groups in a given weight of resin. This ratio can be variedover a wide range. Generally, however, a hydroxyl-carboxyl ratio ofbetween 1.5:1 to 5:1 is needed.

Instead of employing a polycarboxylic compound which is Diels-Alderadduct of hexahalocyclopentadiene and a polycarboxylic compound, apolyhydric alcohol which is a Diels-Alder adduct ofhexahalocyclopentadiene and a polyhydric alcohol can be used. This isdone by employing (A) a polyester resin comprised of the reactionproducts of (1) an adduct of hexahalocyclopentadiene and a polyhydricalcohol containing aliphatic carbon-to-carbon unsaturation, (2) apolycarboxylic compound and (3) a polyhydric alcohol containing at leastthree hydroxyl groups. Typical adducts include:2,3-dimethylo1-1,4,5,6,7, 7-hexachlorobicyclo-(2.2.1)-5-heptene;2,3-dimethylol l, 4,5,6-tetrachloro-7,7-difluorobicyclo-(2.2.1) 5heptene; and the like.

The preferred polyesters of the invention are those which contain anadduct of hexahalocyclopentadiene creacted in the polyester portion inview of the fact that they contain :a large amount of stable halogen,thereby enhancing the flame-retardant characteristics of the resultantfoam. Particularly preferred are those polyesters wherein the adduct isreacted in the polycarboxylic portion of the polyester, due to lowercost and commercial availability of the polycarboxylic adducts ofhexahalocyclopentadiene.

A particularly desirable alkyd resin for use in this invention isprepared by reacting a polycarboxylic compound and a polyhydric alcohol,at least one of which is an adduct of hexahalocyclopentadiene as definedhereinbefore, in a ratio to provide more than one hydroxyl group foreach carboxyl group. The reaction of the components is continued until aresin is produced having an acid number in the range of 20 to 90,preferably 25 to 60. Then an epoxide is introduced to the reactionmixture and the reaction is continued until the resin has an acid numberof less than 20, preferably less than 10 and still more preferably lessthan about 2. The preferred reaction temperature is in the range of 150to 200 degrees centigrade, but higher and lower temperatures can beemployed. The hydroxyl number of the resulting resin'generally is in therange of about 200 to 800, usually from about 300 to 600. The monomericepoxides are generally preferred in preparing the composition, andtypical examples of these are ethylene oxide, propylene oxide, butyleneoxide, cyclohexene oxide, styrene oxide, allyl glycidyl ethcrs, glycidylsorbate, and the like. The preferred compounds are alkylene oxideshaving up to 6 carbon atoms.

The polyethers employed are known in the art, and are the reactionproducts of (1) either a polyhydric alcohol, a polycarboxylic acid or apolyphenolic compound, and (2) a monomeric 1,2-epoxide possessing asingle 1,2- epoxy group, such as, for example, propylene oxide. Thepolyhydric alcohols and polycarboxylic acids which can be employed areany of the polyhydric alcohols and polycarboxylic acids listedhereinbefore. Polyphenolic compounds which can be employed are thereaction products of phenolic compounds with aldehydes, such asphenolformaldehyde novolac resins. Examples of monomeric 1,2- epoxidesinclude ethylene oxide, propylene oxide, butylene oxide, styrene oxide,cyclohexene oxide, allyl glycidyl ether, butyl glycidyl sulfide,glycidyl sorbate, glycidyl allyl phthalate, and the like. The preferredmonoepoxides are the monoepoxide substituted hydrocarbons, themonoepoxy-substituted ethers, sulfides, sulfones and esters wherein thesaid compounds contain no more than eighteen carbon atoms. A loweralkylene oxide having up to 6 carbon atoms, is preferably employed inrigid foams as the higher counterparts yield flexible rather than rigidproducts.

Various polyarylpolyisocyanates which contain an average of at leastthree arylene radicals per molecule can be used in preparing thecompositions of the invention. Especially preferred for use in theinvention are the polyarylpolyisocyanates having the followinggeneralized formula:

I| I(JO I NCO 1 1 0X, OX l wherein n has an average value of at least 1and generally is from 1 to 3. Other typical compounds ofthis typeinclude those wherein the R groups are chlorine, bromine, methyl ormethoxy, and wherein the value of X is methyl or phenyl in the genericformula.

Also useful are polyarylpolyisocyanates having the following formula: I

NCO'l J wherein R and X are as defined hereinbefore, m is a number from3 to 4, p is a number from to 1 and m +p is-4.

Typical compounds have the formulae:

IIICO Mixtures of the compounds are alsouseful.

, Any foaming agent commonly used inthe art can be employed. These aregenerally those materials that are capable of liberating gaseousproducts when heated, or when reacted with an isocyanate. Preferably,foaming is accomplished by introducing a low boiling liquid into theresin. The heat of reaction is then sufiicient to expand the mixture'toa foam stable enough to retain its shape until the resin gels. Suitableliquids are the fluorochlorocarbons boiling in the range of -30 to 50degrees centigrade and mixtures thereof, for example,trichlorofluoromethane, trichlorotrifluoroethane,difluoromonochloroethane, and difluorodichloroethane. Also useful aremixtures of the fluorocarbons with chlorocarbons such as methylenechloride. Another class of foaming agents that is suitable for carryingout the foaming reaction at an elevated temperature is a tertiaryalcohol in combination with a strong concentrated acid catalyst.Examples of tertiary alcohols include: tertiary amyl alcohol; tertiarybutyl alcohol; and the like. Examples of catalysts include sulfuric acidand aluminum chloride. Other foaming agents that can be used include thefollowing: polycarboxylic acids, polycarboxylic acid anhydrides,dimethylol ureas, polymethylol phenols, formic acid and tetrahydroxymethyl-phosphonium chloride.

If desired, a reaction catalyst can be employed in preparing thecomposition of the invention. Generally, but not necessarily, catalystsare employed to prepare the polyurethane foams having densities up toabout 6 pounds per cubic foot. For foam products having densities of 6pounds per'cubic foot and higher, reaction catalysts are generally notneeded. The catalysts employed can be any of the known conventionalcatalysts for isocyanate reactions, but the tertiary amines arepreferred. Many such compounds are useful in the reaction, but theygenerally have up to 20 carbon atoms. Typical compounds of the trialkylamines, such as trimethyl amine, triethyl amine, diethylene triamine,tetramethyl butane diamine and the like. Also suitable are themorpholine compounds such as N-methyl morpholine, N-acetyl morpholine,4,4-dithio morpholine, and the like, and the tertiary amine compoundshave other functional groups such as diethyl ethanol amine, methyldiethanol amine, N-diethyl aminoacetic acid, methyl aminodipropionicacid, N-niethyl dipropylene triamine, dimethyl piperazine, and the like.The preferred amine compounds are triethyl amine and tetramethylguanidine. Other urethane catalysts are also useful, for example: theantimony compounds, such as antimony caprylate, antimony naphthenate,and antimonious chloride; the tin compounds such as dibutyltindilaurate, tri-n-octyltin oxide, hexabutylditin, tributyltin phosphateor stannic chloride.

In preparing the polyurethane compositions of this invention, thehydroxyl-containing polymer and polyisocyanate are preferably reacted ina ratio sufficient to provide about 85 to 115 percent of isocyanatogroups with respect to the total number of hydroxyl and carboxyl groupspresent in the hydroxyl-containing polymeric material (and the foamingagent, if one is provided). The organic phosphonates of the inventionare employed in an amount of at least about 1 part, up to about 20 partsby weight per hundred parts of the hydroxyl-containing polymer. Thepreferred amount of the organic phosphonate is from about 2 to about 10parts by weight per one hundred parts of hydroxyl-containing polymer. Itis generally preferred to add the phosphorus compound directly to thehydroxyl-containing polymer to reduce the viscosity, and subsequently toadd polyisocyanate and the foaming agent; however excellent results areobtained when all the components are simultaneously put together.Thefoaming agent is preferably employed in an amount sufficient toproduce a foam having a density in the range of about 4 to 30 pounds percubic foot, preferably 4 to 20 pounds per cubic foot. The reactiontemperature generally ranges from about 20 to about degrees centigrade,although higher and lower temperatures can be employed. The temperaturesof the components can be adjusted to provide a foarnable composition ina pre-expanded or frothed condition, if desired.

Various additives can be incorporated in the polyurethane composition tomodify the properties thereof. For example, the fire resistance of thecomposition can be further improved by the addition of an antimonycompound. Fillers, such as clay, calcium sulfate or ammonium phosphatecan be added to lower the cost; components, such as dyes can be addedfor color, and fibrous glass, asbestos, synthetic fibers can be added toimprove strength characteristics. Surfactants are generally employed tocontrol cell structure. Suitable cell controllers are thesilicone-glycol copoly mers, such as triethoxy dimethyl polysiloxanecopolymerized with a dimethoxypolyethylene glycol.

The compositions of the invention are useful in a variety ofapplications. For example, the foams having a density in the range ofabout 4 to 6 pounds per cubic foot are useful in constructing specialprotective panels requiring extra strength. The foams having a densityin the range of about 4 to 10 pounds per cubic foot are particularlysuited for use in the construction of radomes. The higher density foams,such as those having densities in the range of 15 to 25 pounds per cubicfoot are useful in applications requiring extra strength such as floorbedding for refrigerator cars, foam-filled panels for use in marineconstruction, and the like.

The following examples serve to illustrate the invention, but are notintended to limit. All parts are by weight and temperatures are indegrees centigrade, unless it is indicated otherwise.

EXAMPLE 1 A mixture of hydroxyl-containing polymers was pre pared byblending the following components: 50 parts of a polyester containing 2moles of trimethylol propane to 1 mole of1,4,5,6,7,7-hexachlorobicyclo-(2.2.1)-5-heptene-2,3-dicarboxylicanhydride, and having a hydroxyl number of about 370; and 50 parts of apolyethylene ether polyol having a hydroxyl number of about 300, and 2.7parts of trimethylol propane. To 200 parts of the foregoing compositionwere added 162 parts of polymethylene polyphenylisocyanate, about onepart of a siliconeglycol copolymer cell controller and 21.8 parts oftrichlorofluoromethane. The mixture was agitated vigorously at 50degrees centigrade for 15 seconds and poured into a mold. After theresulting foam was cured, it was cut into sections. The interior of thefoam was observed to have a very non-uniform cell structureareas ofcoarse cells, areas of fine cellsacross a given crosssection of foam.Some areas of the foam were cracked. The overall density of the foam was4.1 pounds per cubic foot.

EXAMPLES 2, 3, AND 4 In these examples, various quantities of dimethylmethyl phosphonate were incorporated into the mixture ofhydroxyl-containing polymer. The mixtures were then used to makepolyurethane foams in accordance with the procedure of Example 1. Thequantity of foaming agent was increased to maintain a constant ratio inthe total 1 A p01yslloxane-polyoxyalkylene block copolymer prepared inaccordance with the disclosure in U.S. Patent No. 2,834,748.

7. composition. The resulting foams vhad properties shown in Table 1.

no cracking.

EXAMPLES 5, 6, AND 7 In these examples, a mixture of hydroxyl-containingpolymers was prepared by blending 50 parts of polyester containing 2moles of trimethylol propane to 1 mole of1,4,5,6,7,7-hexachloro-(2.2.1)--heptene-2,3 dicarboxylic 8. ing anorganic phosphonate the rein. Other advantages that have been observedare the reduction in the viscosity of the hydroxyl-containing polymersthat result from incorporating the organic phosphonate therein, as wellas overall improvements inthe fire resistance of the'polyurethane foamscontaining the organic'pliosphonates.

While the invention has been described with reference to certainspecific embodiments, it will be recognized by those skilled in the artthat many variations are possible without departing from the spirit andscope of the invention.

We claim:

1. A polyurethane foamed composition having a density of at least fourpounds per cubic foot, and comprising the reaction product of componentscomprising:

(A) a hydroxyl-containing polymer having a hydroxyl number of about 25to 900,

(B) as the sole phosphorus containing component, a

compound having the formula:

anhydride and having a hydroxyl number of about 370; and 50 parts of apolyethylene ether polyol having a RQ. .P .()R hydroxyl number of about300, 2.7 parts of trimethylol I propane and 5.4 parts of diamylamylphosphonate. To 100 parts of the foregoing composition were added 84parts wherein Y is selected from the group consisting of ofpolymethylene polyphenylisocyanate, 1.75 parts of a oxygen and sulfur,and R is selected from the group silicone-glycol copolymer 2 cellcontroller, and various consisting of alkyl, halogen-substituted alkyl,aralkyl, amounts of trichlorofiuoromethane suitable for producingalkaryl and aryl, in a proportion of about 1 to about foams of severaldensities as follows: 20 parts by weight per hundred parts of thehydroxylcontaining polymer; Density, Foaming agent, Polyol Isocyanatc(C) a polyarylpolyisocyanate having the formula: Ex pounds per parts pertemperature, temperature, I 7

cubic foot 100 parts resin F. F. NC 0 N00 NC 0 5 21.8 1 112 92 l y 614.6 4 103 26 7 7.8 9 103 16 OX, OX The mixtures of components wereagitated vigorously and l- I poured into molds. The resulting foams hadproperties R R n R shown in Table 2. In this table comparison is alsomade wherein R is selected from the group consisting of with commercialfoams having densities comparable to the 40 hydrogen, chlorine, bromine,alkyl having 1 to 5 carfoam produced in Example 7. bon atoms, and alkoxyhaving 1 to 5 carbon atoms;

TABLE 2 Example No. Commcr- Commercial cial 5 6 7 foam A foam B Density,pounds per cubic to t 21.8 14.6 7.8 5.9 6.5 Compressive strength,

pounds per square inch:

Parallel at--:

25 c 1, 370 617 216 178 150 80 0-.-- 950 465 155 139 100 100 0... 790405 14s 10s 85 120 0 620 310 100 Perpendicular at 25 0.... 1,280 603 200119 160 Compression strength retention, percent:

Fire resistance:

AS'IM D-757-49, inches per minute 0. 0 0. 66 0. 86 ASIM D169259T,

classification 1 N on-burning.

Following the procedure of Examples 5-7, similar re- X is selected fromthe group consisting of hydrogen, sults are obtained for the followingphosphorus comalkyl having 1 to 10 carbon atoms and phenyl; and 11pounds. has an average value of about 1 to 3; and Exam le 8Bis chloro r01 chloro r0 1 hos honate (D) afoammg agent p py p py p p 2. Thepolyurethane foam of cla1m 1 wherein the phos Example 9-Dimethylmethylthionophosphonate A polysiloxane-polyoxyalkylene block copolymerprepared in accordance with the disclosure in U.S. Patent No. 2,834,748.

phorus compound is diamyl amylphosphonate.

3. The polyurethane foam of claim 1 wherein the phosphorus compound isdimethyl methylphosphonate.

4. The polyurethane foam of claim 1 wherein the phosphorus compound is'bis(chloropropyl) chloropropyl phosphonate.

5. The polyurethane foam of" claim 1 wherein the polyarylpolyisocyanateis polymethylene polyphenylisocyanate. Y

6. The foamed composition of claim 1 wherein the hy- 9 droxyl-containingpolymer comprises a polyester resin comprised of the reaction product ofa polyhydric alcohol and a polycarboxylic compound.

7. The foamed composition of claim 1 wherein the hydroxyl-containingpolymer is a mixture of a polyester comprised of the reaction product ofa polyhydric alcohol and polycarboxylic compound, and a polyethercomprised of the reaction product of a monomeric 1,2-epoxide and amaterial selected from the group consisting of a polyhydric alcohol, apolycarboxylic acid and a polyphenolic compound.

8. The foamed composition of claim 6 wherein the polycarboxylic portionof said polyester contains an adduct of hexahalocyclopentadiene and apolycarboxylic compound, wherein the halogen is selected from the groupconsisting of fluorine, chlorine, bromine and mixtures thereof.

9. The foamed composition of claim 1 wherein the hydroxyl-containingpolymer comprises an alkyl resin prepared by reacting a monomericmonoepoxide with the 9 reaction product of (a) an adduct ofhexachlorocyclopentadiene and a polycarboxylic compound containingaliphatic carbon-to-carbon unsaturation, and (b) a polyhydric alcoholcontaining three hydroxyl groups, said reaction product having an acidnumber in the range of to 90; to produce a product having an acid numberof less than 20.

10. A composition suitable for use in preparing a polyurethane foamhaving a density of four pounds per cubic foot which comprises thecomponents:

(A) a hydroxyl-containing polymer having a hydroxyl number of about to900;

(B) as the sole phosphorus containing component, a

compound having the formula:

II RO-lr-OR R wherein Y is selected from the group consisting of oxygenand sulfur, and R is selected from the group consisting of alkyl,halogen-substituted alkyl, aralkyl, alkaryl, and aryl, in a proportionof about 1 to about 20 parts by weight per hundred parts of thehydroxylcontaining polymer.

11. The composition of claim 10 wherein the hydroxylcontaining polymercomprises a polyester of components comprising a polyhydric alcohol andan adduct of hexahalocyclopentadiene and a polycarboxylic compound,wherein the halogen is selected from the group consisting of fluorine,chlorine, bromine and mixtures thereof, and the phosphorus compound hasthe formula:

wherein R is alkyl.

12. The composition of claim 10 wherein the hydroxylcontaining polymercomprises a polyester of components comprising a polyhydric alcohol andan adduct of hexahalocyclopentadiene and a polycarboxylic compound,wherein the halogen is selected from the group consisting 10 offluorine, chlorine, bromine and mixtures thereof, and the phosphoruscompound has the formula:

0 ROi -OR 1'1 wherein R is halogen-substituted alkyl.

13. A method for preparing a polyurethane foam of improved cellstructure, which has a density of at least four pounds per cubic foot,which comprises reacting a composition comprised of:

(A) a hydroxyl-containing polymer having a hydroxyl number of about 25to 900, and

(B) as the sole phosphorus containing component,

a compound having the formula:

i Ro1 =-0R R wherein Y is selected from the group consisting of oxygenand sulfur, and R is selected from the group consisting of alkyl,halogen-substituted alkyl, aralkyl, alkaryl and aryl, the phosphoruscompound being present in said composition in a proportion of about 1 toabout 20 parts by weight per hundred parts of the hydroxyl-containingpolymer, with a polyaryl polyisocyanate having the formula:

W ,mmj

NCO

n R wherein R is selected from the group consisting of hydrogen,chlorine, bromine, alkyl having 1 to 5 carbon atoms, and alkoxy having 1to 5 carbon atoms; X is selected from the group consisting of hydrogen,alkyl, having 1 to 10 carbon atoms and phenyl; and n has an averagevalue of about 1 to 3, in the presence of a foaming agent. 14. Theprocess of claim 13 wherein the phosphorus compound is diamylamylphosphonate.

15. The process of claim 13 wherein the phosphorus compound is dimethylmethylphosphonate.

16. The process of claim 13 wherein the phosphorus compound isbis(chloropropyl) chloropropylphosphate.

17. The process of claim 13 wherein the polyarylpolyisocyanate ispolymethylene polyphenylisocyanate.

References Cited UNITED STATES PATENTS 3,156,659 11/1964 Robitschek260--2.5

3,203,931 8/1965 Swart 26077.5

3,250,827 5/1966 Schroll 260-25 3,257,337 6/1966 Schoepfle 260-25FOREIGN PATENTS 1,297,489 5/ 1962 France.

OTHER REFERENCES Carwin C0. Technical Bulletin, Papi Derived RigidUrethane Foams, February 1962, 11 pages.

DONALD E. CZAJA, Primary Examiner. M. B. FEIN, Assistant Examiner.

